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    <title>obs_gram</title>
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    <center>Scilab Function</center>
    <div align="right">Last update : April 1993</div>
    <p>
      <b>obs_gram</b> -  observability gramian</p>
    <h3>
      <font color="blue">Calling Sequence</font>
    </h3>
    <dl>
      <dd>
        <tt>Go=obs_gram(A,C [,dom])  </tt>
      </dd>
      <dd>
        <tt>Go=obs_gram(sl)  </tt>
      </dd>
    </dl>
    <h3>
      <font color="blue">Parameters</font>
    </h3>
    <ul>
      <li>
        <tt>
          <b>A,C</b>
        </tt>: real matrices (of appropriate dimensions)</li>
      <li>
        <tt>
          <b>dom</b>
        </tt>: string (<tt>
          <b>"d'</b>
        </tt> or <tt>
          <b>"c"</b>
        </tt> (default value))</li>
      <li>
        <tt>
          <b>sl</b>
        </tt>: <tt>
          <b>syslin</b>
        </tt> list</li>
    </ul>
    <h3>
      <font color="blue">Description</font>
    </h3>
    <p>
    Observability gramian of the pair <tt>
        <b>(A,C)</b>
      </tt> or linear 
    system <tt>
        <b>sl</b>
      </tt> (<tt>
        <b>syslin</b>
      </tt> list).
    <tt>
        <b>dom</b>
      </tt> is the domain which can be 
  </p>
    <dl>
      <dd>
        <b>"c"</b>:  continuous system (default)</dd>
      <dd>
        <b>"d"</b>:  discrete system</dd>
    </dl>
    <h3>
      <font color="blue">Examples</font>
    </h3>
    <pre>

A=-diag(1:3);C=rand(2,3);
Go=obs_gram(A,C,'c');     // &lt;=&gt; w=syslin('c',A,[],C); Go=obs_gram(w);
norm(Go*A+A'*Go+C'*C,1)
norm(lyap(A,-C'*C,'c')-Go,1)
A=A/4; Go=obs_gram(A,C,'d');    //discrete time case
norm(lyap(A,-C'*C,'d')-Go,1)
 
  </pre>
    <h3>
      <font color="blue">See Also</font>
    </h3>
    <p>
      <a href="ctr_gram.htm">
        <tt>
          <b>ctr_gram</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="obsvss.htm">
        <tt>
          <b>obsvss</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="obsv_mat.htm">
        <tt>
          <b>obsv_mat</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="../linear/lyap.htm">
        <tt>
          <b>lyap</b>
        </tt>
      </a>,&nbsp;&nbsp;</p>
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